Final answer:
The long-term expected output capability of a resource, also known as energy return on energy investment (EROEI), is the amount of energy output a resource will provide over its lifetime relative to the energy input required to develop it. For example, a resource with a 10:1 EROEI over a 40-year lifespan will return 10 times the energy initially invested, and if 10 qBtu are invested with this EROEI, the resource will produce 100 qBtu over its lifetime.
Step-by-step explanation:
The long-term expected output capability of a resource or system is commonly referred to as its energy return on energy investment (EROEI). This metric helps in understanding how much energy a resource can provide over its lifetime compared to the energy invested in developing and exploiting it.
An EROEI figure of 6, as mentioned, implies that for every unit of energy invested to harness the resource, a total of 6 units of energy are returned over the resource's operational life. This is analogous to the simpler R/P ratio, which is reserves to production ratio, a fundamental way to estimate the timescale for resource availability. If, for instance, a resource with a 10:1 EROEI is developed over 40 years, it would require 4 years of energy output to cover the development costs.
For example, if the U.S. invests 10 quadrillion British thermal units (qBtu) in building a new energy infrastructure with a 10:1 EROEI that lasts 40 years, this new resource would produce 100 qBtu over its lifetime and approximately 2.5 qBtu per year. Considering the initial one-time investment of 10 qBtu, the energy put in would be returned in 4 years.
This calculation helps in understanding the concept of sustainable resource management and guides decisions on whether a particular resource should be exploited or if the resulting output is deemed inadequate for the long-term demands.